Preheat the oven to 400°F.
Add the dry ingredients in a bowl and mix to disperse the baking powder and sweetener.
Add the cold water and melted butter, forming a dough with your hands. (Start with 2 tablespoons of water and slowly add more until the mixture is no longer crumbly).
Form dough into a disc, wrap in plastic, and refrigerate for 30 minutes.
Roll out the dough between plastic wrap pieces and then transfer it to a greased 9-inch pie tin.
The dough will fit the pan exactly; you might have to work it with your fingers. It will feel thin, but the baking powder helps it puff up a bit.
Bake the crust for 25 minutes with pie weights (line the crust with foil or parchment and fill with dry rice or beans).
Remove the pie weights and bake the crust for 10 to 15 minutes longer or until it is thoroughly baked and golden brown.